The present invention generally relates to identification of implanted leads, such as of an implantable medical device (IMD). More particularly, the present invention relates to implanted lead sleeves having RFID tags associated therewith.
It would be beneficial if physicians were able to obtain additional information about an implanted device and/or a patient from an implanted identification tag. Such information would preferably include, in addition to the manufacturer and model number of the device, the serial number of the device, the date of manufacture, the treating physician's name and contact information and, if authorized by the patient, the patient's name, contact information, medical condition and treatment, and other relevant information concerning device programmed parameters and the like. There are many potential benefits from being able to determine the specific model and serial number and additional related device or patient information in an implanted medical device or associated lead system. For example, product recalls are an increasingly complex and extensive problem, and the ability to rapidly identify the precise model and serial number of an implanted product may be life-saving. Cost savings for the involved company may also be substantial. Such implanted products may be either passive or active, and include things like stents, heart valves, neoplant hardware, and hip implant hardware or the like. They may also include external devices like Holter monitors, external pacemakers, and so forth.
Currently, most IMD patients carry some sort of identification. This may be in the form of a card carried in the wallet or an ID bracelet indicating, for example, that the patient is a pacemaker wearer of a certain model and serial number. However, such forms of identification are often missing or not up to date. In addition, manufacturers' databases and related patient cardiac rhythm management device (CRMD) system cards are frequently incomplete and/or inaccurate. It is quite common for an elderly patient to be presented at the emergency room (ER) of a hospital without his or her wallet and without wearing or carrying any type of a bracelet or other identification. In addition, there have been a number of situations where the patient (due to dementia or Alzheimer's, etc.) cannot clearly state that he or she even has a pacemaker.
There are known in the art various methods for identifying implanted medical devices. One such method is the use of X-ray identification tags encapsulated within header blocks of cardiac pacemakers or implantable cardioverter defibrillators (ICDs). Such X-ray identification tags can be read on an X-ray of the implanted device and provide information to the physician. The information so provided is very limited due to space and typically includes only the manufacturer or the model number of the implanted device. In an emergency, the time delay to obtain X-ray films can also be problematic.
Oftentimes the ER physician will palpitate the patient's chest and feel that there is an implanted device present. If the patient is comatose, has low blood pressure, or is in another form of cardiac distress, this presents a serious dilemma for the physician. At that moment, all that the physician knows is that the patient has some sort of IMD implant. It could be a pacemaker, a cardioverter defibrillator (ICD), a vagus nerve stimulator, a deep brain stimulator or other type of neurostimulator, or a variety of other therapeutic and/or monitoring devices. What happens next is both laborious and time consuming. The ER physician will have various manufacturers' cardiac rhythm management device (CRMD) programmers transported from the hospital pacemaker or ICD follow-up clinic or other site down to the ER. ER personnel will then try to interrogate the implantable medical device to see if they can determine what it is. For example, they might first try to use a Medtronic programmer to see if it is a Medtronic pacemaker. If unsuccessful, they might try a St. Jude, a Guidant, an ELA, a Biotronik or one of a number of other programmers that may be available. If none of those programmers work, then the ER physician has to consider that the implanted device may be a neurostimulator and perhaps secure a Cyberonics or Neuropace programmer. It may also be that the telemetry programming wand is mal-positioned as this can be quite sensitive or that the implanted device has failed, etc.
It would be a great advantage and potentially lifesaving if the ER physician (or ambulance emergency medical technician) could very quickly identify, at a minimum, the type of implant, manufacturer and model number using a generic RFID reader. In certain cases, for example, with a pacemaker patient who is in cardiac distress, quickly identifying and obtaining the appropriate external programmer could allow the ER physician or other trained personnel to boost the pacemaker output voltage and/or pulse rate to properly recapture the heart, obtain a regular rhythm and stabilize blood pressure. A variety of other programmable stabilizing adjustments may also be made as required. All of the time lost while trying to identify the right programmer can be detrimental not only to the patient, but also detract attention from other critical tasks for that patient and for other patients in the ER. Accordingly, there is a need for a way to rapidly identify the type and model number of all IMD so that the proper external programmer for it can be rapidly identified and obtained, and/or other appropriate activities initiated. The teachings of U.S. Patent Application Publication No. US 2006/0212096 A1 are incorporated herein by reference.
It is also important to note that pulse generator or IMD lead systems generally remain in the human body much longer than the IMD itself. For example, in the case of a cardiac pacemaker, the pulse generator power cell (battery) may last for three, five or even up to 10 years depending on a variety of program settings and other features, whereas leads (the insulative conductors connecting the pulse generators to the heart) typically have a very low failure rate even after 10 years in the human body. Changing the pulse generator is, from a technical perspective, a relatively minor procedure whereas the removal of leads from the heart, once they have been implanted for greater than six months to a year, requires relatively sophisticated equipment and surgical skill and is considerably more risky for the patient. This is because the lead insulation tends to become embedded and overgrown by scar tissue. This can involve the whole length of the lead and tends to be particularly dense in the great veins, adjacent to a heart valve and adjacent to electrodes. Thus, on occasion, even open heart surgery may be required to remove lead systems. In contrast, when a pacemaker is replaced, the tissue over the pulse generator is simply incised, the old pulse generator disconnected and the existing lead plugged into the new pacemaker.
Unfortunately, it is not uncommon for leads to fail for various reasons. They could fail due to breakdown of the insulation, fracture of the conductor, etc. Leads may also be abandoned because they have migrated to an improper position within the heart, etc. When a lead is abandoned, the physician normally snips off the connectors and tags the remnants in the adjacent tissue. New leads are then implanted often in parallel with the old abandoned leads. Abandoned leads are often well tolerated, but there is also extensive literature on the complications they can cause, including venous obstruction, infection, tachyarrhythmias, damage during MRI procedures and many others.
For example, it has been demonstrated in the literature that during an MRI procedure, leads (abandoned or live) can greatly overheat due to the powerful RF and magnetic fields induced during MRI. Accordingly, it is important that there be a way of identifying not only the presence of abandoned leads, but also the precise lead type and model. This applies not only during follow-up of complex patients (and they are common), but also when device patients are presented to an Emergency Room under various circumstances. Regardless of the circumstances under which a medical practitioner may contemplate performing a medical diagnostic procedure on the patient such as MRI, that patient, and in fact, all patients, will be well served by caregivers being able to rapidly and efficiently identify the make and model number of all IMDs, all leads and other components, like adapters, and all other implanted foreign materials whether functioning or abandoned. In addition, such technology should also improve the efficiency of product recall management.
It is also important to note that certain lead systems are evolving to be compatible with specific types of medical diagnostic procedures. For example, US 2009/0163981 A1 and US 2006/0247684 A1, both of which are herein incorporated by reference, disclose the use of bandstop (tank) filters placed in series with leads or circuits of active medical devices to enhance their MRI compatibility. MRI systems vary in static field strength from 0.5 Tesla all the way to above 10 Tesla. A very popular MRI system, for example, operates at 3 Tesla and has a pulsed RF frequency of 128 MHz. There are specific certain lead systems that are evolving in the marketplace that would be compatible with only this type of MRI system. In other words, it would be dangerous for a patient with a lead designed for 3 Tesla to be exposed to a 1.5 Tesla system. Thus, there is also a need to identify such lead systems and their associated IMDs for medical personnel (such as the MRI technician or radiologist) when necessary, and to warn against potential highly dangerous therapeutic and diagnostic interventions. Therefore, there is a need to associate an RFID tag with both the IMD and its associated leads. For example, a patient that has a lead system that has been specifically designed for use with a 3 Tesla MRI system may have several pacemaker replacements over the years. It is important that the replacement pacemakers be 3 Tesla compatible and be compatible with the leads if the patient is to safely receive an MRI scan.
Accordingly, there is a continuing need for methods and means for associating RFID tags with IMDs, and particularly implanted leads thereof. Moreover, there is a continuing need for associating RFID tags with abandoned leads. There is further a continuing need to provide effective means for associating such RFID tags or other identifiers to such leads. The present invention fulfills these needs and provides other related advantages.